/**
 * Definition for singly-linked list.
 *  */
 class ListNode {
      int val;
      ListNode next;
      ListNode() {}
      ListNode(int val) { this.val = val; }
      ListNode(int val, ListNode next) { this.val = val; this.next = next; }
  }
class Solution {
    public ListNode reverseList(ListNode head) {
        ListNode cur = head.next;
        ListNode pre = head;
        ListNode tem;
        while(cur!=null) {
            tem=cur.next;
            cur.next=pre;
            pre=cur;
            cur=tem;
        }
        return pre;
    }
}
public class lc206 {
}
